1. Field of the Invention
The present invention relates to a presence update system and method therefor, and a mobile communication terminal and a non-contact communication apparatus used therefor, in particular, to a presence update system for generating up-to-date presence information indicating the location and condition of a user of a mobile communication terminal to update presence information with the presence information.
2. Description of the Prior Art
Recently, an IM (Instant Message) service and a PoC (Push to talk over Cellular) service have spread as services using a mobile phone. The IM service is a service like e-mail but is different from the e-mail in that it transmits and receives data in real time. The PoC service is a service having a function like the function of a transceiver, which is capable of performing one-to-one or one-to-many communication utilizing a mobile phone network.
In such services, it is necessary to check the condition of a communication counterpart. In communication means such as PoC, it is necessary to check the condition of a counterpart (referred to as “presence”) before starting communication, unlike a telephone. This is because, if the counterpart is not in a condition capable of communication, no reply is returned even if PoC is used to call the counterpart, and communication is not established. It is also necessary that the presence should always indicate the up-to-date condition. Even if the presence is checked and communication is requested, communication is not established unless the communication counterpart has updated the presence.
This problem can be solved by continuously updating the presence. However, since a user is required to perform some operations to update the presence, the presence is often not updated for some time in the case of a mobile phone always carried with the user. Thus, though the presence is very important and useful in communication between mobile phones, it actually is not effectively utilized.
With reference to Japanese Patent Laid-Open No. 2003-274440, a technique is disclosed in which the presence of a mobile telephone is updated, transmitted to a server and registered with the server, with the use of a location information service of a base station for a mobile communication network.
In the case of utilizing communication by the above-described PoC service, a communication counterpart may be selected by checking the presence, which is the condition of the communication counterpart. This presence notifies information about the location and condition of the counterpart, whether communication is possible or not, and the like, which is important information for a mobile phone which moves together with a user, as described above.
However, the user of a mobile phone is required to change the presence by a manual operation according to his condition and location, and input by the mobile phone is annoying and troublesome. Furthermore, since the user always carries the mobile phone to use it, the condition or location of the user frequently changes. It is a heavy burden for the user to change the presence every time his condition or location changes. As a result, the user feels it troublesome to input the presence, and the presence is left unupdated.
According to the technique in Japanese Patent Laid-Open No. 2003-274440, the presence is automatically updated with the use of a location information service of a base station. However, though the location information is automatically updated, information about the condition of a user must be updated by operation by the user, which is, after all, a burden on the user.
The object of the present invention is to provide a presence update system capable of eliminating a manual operation by a user to reduce a burden on the user.